//
// NestedDiagnosticContext.h
//
// Library: Foundation
// Package: Core
// Module:  NestedDiagnosticContext
//
// Definition of the NestedDiagnosticContext class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_NestedDiagnosticContext_INCLUDED
#define Foundation_NestedDiagnosticContext_INCLUDED


#include <ostream>
#include <vector>
#include "Poco/Foundation.h"


namespace Poco
{


class NDCScope;


class Foundation_API NestedDiagnosticContext
/// This class implements a Nested Diagnostic Context (NDC),
/// as described in Neil Harrison's article "Patterns for Logging
/// Diagnostic Messages" in "Pattern Languages of Program Design 3"
/// (Addison-Wesley).
///
/// A NDC maintains a stack of context information, consisting of
/// an informational string (e.g., a method name), as well as an
/// optional source code line number and file name.
/// NDCs are especially useful for tagging log messages with
/// context information which is very helpful in a multithreaded
/// server scenario.
/// Every thread has its own private NDC, which is automatically
/// created when needed and destroyed when the thread terminates.
///
/// The NDCScope (or NDC::Scope) class can be used to automatically
/// push information at the beginning of a scope, and to pop it
/// at the end.
/// The poco_ndc(info) macro augments the information with a
/// source code line number and file name.
{
public:
    typedef NDCScope Scope;

    NestedDiagnosticContext();
    /// Creates the NestedDiagnosticContext.

    NestedDiagnosticContext(const NestedDiagnosticContext & ctx);
    /// Copy constructor.

    ~NestedDiagnosticContext();
    /// Destroys the NestedDiagnosticContext.

    NestedDiagnosticContext & operator=(const NestedDiagnosticContext & ctx);
    /// Assignment operator.

    void push(const std::string & info);
    /// Pushes a context (without line number and filename) onto the stack.

    void push(const std::string & info, int line, const char * filename);
    /// Pushes a context (including line number and filename)
    /// onto the stack. Filename must be a static string, such as the
    /// one produced by the __FILE__ preprocessor macro.

    void pop();
    /// Pops the top-most context off the stack.

    int depth() const;
    /// Returns the depth (number of contexts) of the stack.

    std::string toString() const;
    /// Returns the stack as a string with entries
    /// delimited by colons. The string does not contain
    /// line numbers and filenames.

    void dump(std::ostream & ostr) const;
    /// Dumps the stack (including line number and filenames)
    /// to the given stream. The entries are delimited by
    /// a newline.

    void dump(std::ostream & ostr, const std::string & delimiter) const;
    /// Dumps the stack (including line number and filenames)
    /// to the given stream.

    void clear();
    /// Clears the NDC stack.

    static NestedDiagnosticContext & current();
    /// Returns the current thread's NDC.

private:
    struct Context
    {
        std::string info;
        const char * file;
        int line;
    };
    typedef std::vector<Context> Stack;

    Stack _stack;
};


typedef NestedDiagnosticContext NDC;


class Foundation_API NDCScope
/// This class can be used to automatically push a context onto
/// the NDC stack at the beginning of a scope, and to pop
/// the context at the end of the scope.
{
public:
    NDCScope(const std::string & info);
    /// Pushes a context on the stack.

    NDCScope(const std::string & info, int line, const char * filename);
    /// Pushes a context on the stack.

    ~NDCScope();
    /// Pops the top-most context off the stack.
};


//
// inlines
//
inline NDCScope::NDCScope(const std::string & info)
{
    NestedDiagnosticContext::current().push(info);
}


inline NDCScope::NDCScope(const std::string & info, int line, const char * filename)
{
    NestedDiagnosticContext::current().push(info, line, filename);
}


inline NDCScope::~NDCScope()
{
    try
    {
        NestedDiagnosticContext::current().pop();
    }
    catch (...)
    {
        poco_unexpected();
    }
}


//
// helper macros
//
#define poco_ndc(func) Poco::NDCScope _theNdcScope(#func, __LINE__, __FILE__)


#if defined(_DEBUG)
#    define poco_ndc_dbg(func) Poco::NDCScope _theNdcScope(#    func, __LINE__, __FILE__)
#else
#    define poco_ndc_dbg(func)
#endif


} // namespace Poco


#endif // Foundation_NestedDiagnosticContext_INCLUDED
